Tuesday, August 31, 2021

Potatoes to plastic: turning potato starch into plastic

The image shows the page from the CIEC website where the resource, Potatoes to plastic, can be downloaded.
This is the second in a series of three posts about CIEC's latest free resource: Potatoes to plastic.

In the previous post I described how potato starch could be easily extracted from potato peel using simple equipment that is readily available in the primary classroom.  Here I will explain how the extracted starch can be used to make bio plastic in a few straightforward steps.  As this quote from a year 5 teacher shows, this activity is not only very engaging, but makes relevant links to the topic of Materials in the English and Northern Irish primary curricula, Earth's Materials in the Scottish curriculum and Myself and non-living things in the Welsh curriculum.

"They have absolutely loved this learning. Thank you for the opportunity to engage Year 5 in such an exciting and relevant project, which has reinforced their previous scientific learning of properties of materials (and has done so in a real-life context they will not forget!) as well as their scientific thinking. This project has led to many wonderful opportunities for cross-curricular links to reading, writing and maths too".

The procedure is even better if you are able to borrow a magnetic hotplate from a local secondary school or University, as can be seen in this demonstration.  However, even without access to this piece of scientific equipment the activity can still be carried out in a saucepan on a cooker hob.

To turn it into plastic, the potato starch need to be mixed with a small quantity of water, glycerin and white vinegar before it is heated.   The mixture is then spread out on a petri dish or saucer and left to harden.  After two or three days these simple ingredients will have set into bio-plastic.  The properties will vary depending upon the exact ratio of the ingredients and how thickly it was spread while drying.  The resource gives guidance as to how children could then investigate the properties of the finished plastic as they explore how it could be used in place of plastics derived from petrochemicals.
Children are invariably delighted with the finished bio-plastic
Experienced teachers will know that even the most engaging activity needs to be planned carefully if the potential learning is to take place. Consequently, the resource gives additional  guidance  including vocabulary prompt cards which support children to use the correct terminology as they describe what has happened.  This also supports them to link the experience to past science learning.

Children using the list of vocabulary to support them to talk about the activity in a more scientific way.

In the final post in this series I will explain how this resource can be used in English lessons and to develop children's understanding of how science is working to find solutions to other environmental problems.  
Full instructions including health and safety advice can be found in the free resource available from our website.

This post was written by Jane Winter who is one of our advisory teachers who works in Lincolnshire and Yorkshire.

Tuesday, August 10, 2021

Potatoes to plastic: Extracting starch from potato peel

This is the first in a series of three posts which have been written by one of our advisory teachers, Jane Winter.  They are based upon our latest free resource: Potatoes to Plastic

Frequently, scientists are the bearer of bad news.  Every day we read about mounting evidence of climate change, loss of bio-diversity and the prevalence of micro-plastics in the ocean. However, did you know that as well as identifying environmental problems scientists are able to develop solutions to some of them?  The world leading Centre of Excellence in Green Chemistry where scientists work on finding new ways to overcome ecological issues is based at the University of York.

CIEC has been working with some of the scientists from Green Chemistry to develop our latest resource, Potatoes to Plastic which looks at how scientists have been able to develop useful products from a range of waste materials which might otherwise go to landfill.  As well as looking at several examples of this scientific approach to environmental problems, this free publication looks at one example, making bio-plastic from potato peel, in more depth.  Teachers are supported to carry out some straight forward activities with their class which link closely to the materials strand of the KS2 science program of study.  They extract starch from a waste product, potato peel, and then turn that starch into plastic.

Extracting starch from potato peel does not require a lot of expensive equipment. 

I have found the raw material for this activity easy to source.  Although not all chip shops peel their own potatoes, once you find one that does they will almost certainly be prepared to let you have the peel for free. Alternatively, you may find that your school dinner provider is able to give you some.  Another possibility is to use wrinkly old potatoes that have started to sprout and which might otherwise have been thrown away.

Blending the potato peel with water

First of all you will need to blend the peel and a generous quantity of water in a food processor or blender. Give each pair of children a small jug full of the mixture each.  They will need to filter the peel and water mixture by squeezing it through the foot of an old pair of tights or pop socks.  This will produce a white liquid which is a mixture of potato starch and water.  The rest of the solids are left behind and can be disposed of on a compost heap.

Pouring the blended potato peel and water into a pop sock.

After a few minutes the potato starch will start to settle at the bottom of the container.  Once this has happened the water can be poured carefully off to leave behind the wet starch.  At this point children will be amazed to find that they are left with 'oobleck' which is usually made by mixing cornstarch and water.  That is because the starch found in potatoes is exactly the same as starch found in corn.  Once children have finished playing with the oobleck it will need to be left in a shallow container such as a saucer or petri dish to dry.  After a few days all of the water will have evaporated and you will be left with dried potato starch.  

In the next post I will explain how you can turn the potato starch into plastic.  However, if you cannot wait why not check out the full instructions for both activities on the website.  This includes teachers' notes, children's activity sheets and health and safety advice.  This is what one teacher who recently carried out the activity with their class had to say about it.

'Absolutely fantastic! The children have never felt so alive, enthused and engaged in a science lesson that I have taught. They absolutely loved the practical element of blending the potatoes, filtering the starch and using interesting 'ingredients' to create the plastic. Their scientific skills were so clear and they were all extremely careful in measuring their resources and ensuring the investigation plan was carefully followed. The time taken for the excess water to evaporate and leave the powdered starch behind kept them even more engaged as they spoke about nothing for days until it was ready to use'.